1. Field of the Invention
The present invention relates in general to secondary cells and, more particularly, to an electrolytic cell and electrolytic process associated therewith, wherein the formation and growth of a passive layer is substantially suppressed or controlled through the use of a cavitand.
2. Background Art
Rechargeable, or secondary electrolytic cells, have been known in the art for many years. Furthermore, secondary cells constructed with lithium source anodes have likewise been known in the art. Although such lithium rechargeable batteries have proven to be functional, they have been known to have certain limitations. Indeed, it is well known that the cycle life of such rechargeable lithium batteries may be cut relatively short (compared to other types of secondary cells such as nickel-cadmium) due to the formation and growth on the lithium electrode of a passive film or layer, which promotes, during electrodeposition, the formation of dendrites which typically facilitate the loss of electrochemical activity within the cell and/or internal shorting therewithin. When a lithium carbon electrode is used as the lithium source anode, the formation or growth of the passive film or layer greatly decreases the reversibility of the electrode, limiting its energy density. While various approaches have been implemented in an attempt to suppress passive film formation within an electrolytic cell, most approaches have been directed to electrolyte and surface modifications. In the present invention, cavitands are positioned within an electrolytic cell for purposes of controlling the formation and growth of a passive film or layer, and, in turn, dendritic growth.
While cavitands, in general, have been applied for use in various applications, such as chemically modified field effect transistors for potentiometric detection of charged species and in mass sensitive devices for the detection of neutral molecules, among other places, they have not been applied in an electrolytic cell, let alone used for purposes of controlling the formation and growth of a passive film or layer. Indeed, the unique property of using a cavitand in an electrolytic cell is its ability to preferentially attract ions out of the electrolyte, and to follow (or float above) the surface of the alkali metal electrode and maintain contact with the alkali metal electrode irrespective of changes in the surface volume of the electrode due to electrodeposition.
It is thus an object of the present invention to provide an electrolytic cell and associated process wherein the electrolytic cell includes a cavitand associated with the electrode and the electrolyte.
It is also an object of the present invention to provide an electrolytic cell and associated process wherein the cavitand releasably attracts particular ions, such as lithium ions, which are in the electrolyte.
It is still further an object of the present invention to provide an electrolytic cell wherein the cavitand is anchored to a metal ion source electrode regardless of fluctuations to the surface of the electrode typically caused from deposition and/or dissolution of the particular ions.
It is another object of the present invention to provide an electrolytic cell wherein growth and/or formation of a passive film or layer, on a lithium source electrode, is substantially precluded and/or controlled.
It is also an object of the present invention to provide an electrolytic cell and associated process wherein the particular ions attracted by the cavitand are released from the cavitand and substantially uniformly deposited on the electrode to, in turn, substantially suppress dendritic growth.
These and other objects of the present invention will become apparent in light of the present Specification, Claims and Drawings.